Kate Thoma recently came upon a construction zone in Bloomington, and with traffic backed up in the left lane, she zoomed along in the unoccupied right lane until signs told her to move over. She was zipper merging, but her efforts were thwarted by a left lane vigilante who would not let her in line.
“I’m certain he thought of me as rude and entitled, but I was just doing what my 9th grade driver’s ed teacher taught me,” Thoma said.
Indeed zipper merging is the law, but Thoma’s experience prompted her to ask why Minnesotans can’t zipper merge and why some motorists get all worked up when people do it...
The Minnesota Department of Transportation in the early 2000s was the first in the nation to employ the zipper merge as a way to better manage traffic when a lane is closed in work zones. The concept is simple: Drivers remain in their respective lanes until they reach the designated merge point. Then, like we learned in kindergarten, drivers are supposed to take turns falling orderly in line.
“It’s a great idea in theory, but theory is not how people always drive,” said Dwight Hennessy, a traffic psychologist who teaches at Buffalo State College in New York. “Zipper works when everyone follows the rules — the system can handle the odd rule breaker — but typically when one person breaks those rules others often follow.”
When people speed by in the open lane, that ticks people off as those waiting in line for a long time perceive those passing by as being impatient rule breakers sneaking to the front, Hennessy said.
“It’s perceived unfairness,” said MnDOT work zone engineer Ken Johnson. “If more people would use lanes to the merge point, fairness is taken care of.”
Sometimes frustrated drivers take things into their own hands. Thoma has seen drivers intentionally blocking the open lane so nobody can pass. That’s a no-no, said Lt. Gordon Shank of the State Patrol, and a ticketable offense.There's more information at the StarTribune. Frankly I didn't realize it's "the law" (perhaps it varies by state).